Unconnected Bluetooth devices can be in two different modes page scan mode and/or inquiry scan mode. In page scan mode, the Bluetooth device listen for page messages, i.e. requests to establish a connection between the Bluetooth device and the target devices. This is done by periodically operating a receiver of the Bluetooth device and listening for a page message according to the standardized paging procedure in Bluetooth.
The inquiry scan mode is a procedure where the Bluetooth device listens for inquiry messages, i.e. requests for the address of neighboring devices. The address is a prerequisite for the paging procedure and inquiry is needed if the address is not available by other means. This is done by periodically operating a receiver of the Bluetooth device and receiving an inquiry message from the target devices. The target device listens for an inquiry reply according to the standardized inquiry procedure in Bluetooth. The Bluetooth device then goes into the page scan mode to establish connection between the Bluetooth device and the target device. In both the page and inquiry scan modes, the Bluetooth device can repeatedly perform the functions mentioned above if there are no active connections established; thus, power consumption in both modes can waste battery life.